# Questions tagged [relational-calculus]

For questions: (a) about one of the relational forms of predicate calculus, i.e., domain and tuple, or (b) about expressing queries on data contained in a relational database utilizing one of those forms of calculus.

20 questions
Filter by
Sorted by
Tagged with
176 views

### SQLite Calculating percentage with last week values

I have the following table transactions I need to calculate the percentage of growth for total transaction per day with past same day last week A simple way for my transactions table structure --------...
1 vote
121 views

### How can I calculate the cost of the query, if there is a `between` condition?

How can I calculate the cost of the query, if there is a between condition? Select * From A Where A.id between 10 and 50 If Index not exists and there is only one condition: Search in B+ tree to ...
• 197
2k views

### Delete duplicate keys with relation algebra

Hi I am new to databases and relational algebra. I was wondering if there is a way to remove the tuples from a table using relational algebra that have the same keys but different value. e.g. I want ...
• 3
1 vote
99 views

### Find names of persons who own at least one house in each city in Canada using tuple relational calculus

I am working on the following exercise: Using tuple relational calculus, find names of persons who own at least one house in each city in Canada. The relevant relation schemas are: City (city-...
• 11
611 views

### Declarative and Procedural Query Languages

In the book Database System Concepts 6th Edition, Chapter 2 (Relational Algebra), it states that there are three formal query languages, the relational algebra, the tuple relational calculus and the ...
241 views

### Confusion with Tuple Relation Calculus Operations

I came upon a question like, Given the following relational schemas Student (studId, name, age, sex, deptNo, advisor) Department (deptId, DName, hod, phoneNo) Which of the following will be the ...
• 123
909 views

### Questions Concerning the Chase Test

[5 Marks] Let R(A,B,C,D,E) be decomposed into relations with the following three set of attributes {A,B,C}, {B,C,D}, and {A,C,E}. For each of the following sets of FD's, use the chase test to tell ...
88 views

### Converting from domain calculus to relational algebra

At university I have been given these three relations: Customer (Name, City, Account) Offer (Product_Description Supplier, Price) Order (Name, Product_Description, Quantity, Supplier) and this ...
• 63
872 views

### Counting in Tuple Relational Calculus

Given the following schema: Staff (sid, sname) Project (pid, pdesc, pfrom, pto) Asset (aid, acat, adesc) Workfor (sid, pid, wfrom, wto) Assignment (aid, sid, pid, afrom, ato) Note: The bold ...
• 131
223 views

### Difference Between Implication and Conjunction in Domain Relational Calculus

I was reading my notes, and I came across this: Another example would be to find the names of the lecturers teaching all modules. We might reach for the following incorrect expression: {<N&...
• 91
1 vote
441 views

### Quantifiers in Tuple Relational Calculus (Existencial and Universal)

Suppose this state for the relation schema Company I'm stuck trying to understand how, why and when I should use Quantifiers (Existencial and Universal) Examples: Here I understand how the ...
10k views

### Converting SQL to Relational Algebra / Calculus

I have designed a schema and generated a few SQL queries. I'm using PostgreSQL. For example: CREATE TABLE train ( train_code SERIAL PRIMARY KEY, name TEXT NOT NULL ); CREATE TABLE journey ( ...
• 127
1 vote
1k views

### A tuple relational calculus equivalent for the given SQL query

Well, here's a SQL query: select Employee.Name,Department.Name from Employee,Department where Employee.Dept_no=Department.No I have tried a tuple relational calculus on it as: {t|Ǝ s ∈ Employee (s[...
• 143
473 views

### How to express functional dependency in relational calculus and SQL?

I want to express in relational calculus and SQL the following functional dependency associated with Vote. This is the first time I try to implement it in actual SQL and relational calculus. Vote: #...
2k views

### Creating relationships between tables that where not specified in the given UML diagram

Good evening! I'm working on designing my very first actual database from the following UML class diagram (in French unfortunately): I'm at the point of creating the relational sketch of it which I ...
1 vote
173 views

### How to express inclusive and exclusive relations in relational algebra and relational calculus?

Let be the following simplified database sketch: R1(P,S),R2(S,T) and R3(T,S) with P= people S = Sport and T= Sports Center How to find in relational algebra and relational calculus which couples ...
1k views

### What are the practical uses for relational calculus?

In my Database Design course we are learning both Relational Algebra and Relational Calculus. I can see where Relational Algebra could be useful since it is closely tied to SQL. Our professor said ...
65 views

### TRC: Select an ID if it appears on all measurements

I have these two "tables": Station (station_id, city) // Stations details Rainfall (station_id, date, amount) // Rainfall measurements With Tuple Relational Calculus (TRC), I need to ...
• 123
10k views

### Find the highest graded student using Tuple Relational Calculus

Suppose I have a table of students, containing their ID and their grade: ----------------- | id | grade | ----------------- | 1 | 83 | | 2 | 94 | | 3 | 92 | | 4 | 78 | ...
• 253
1 vote